The long range objective of these studies is to evaluate the role(s) of cyclic nucleotides in blood vessels, especially regarding the response of vascular smooth muscle to catecholamines and other vasoactive agents. The specific aims are: 1) The determination of cycic AMP and cyclic GMP in vascular tissue in response to agents that induce contraction or relaxation. 2) The characterization of cyclic nucleotide phosphodiesterase in vascular tissue. 3) The characterization ofadenylate and guanylate cyclase activites in vascular tissue. 4) The evaluation of effects of exogenous cyclic nucleotides and derivations on vascular contraction.